<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<script>
		var a = 123;
		var b = (function () {
			console.log(a);
		}());


		// GO {
		// 	a:undefined;123
		// 	b:undefined;
		// }
	</script>
</body>
</html>